Earlier quoted context omitted.
They also nickel and dime the adults, but only the ones who make the games. It's fine though, because they're nice to players and they've brainwashed them into giving their money to Valve instead of to the developers who actually make the games they fucking play.
When I'm interested in an indie game, I always go first to the developer's website to see if I can just buy a copy directly from them. The vast, vast majority of the time I have to buy it through Steam, maybe Epic, and itch/gog if I'm lucky. It's vanishingly uncommon for them to host the game themselves.
Same reason to embed your trailer on your site with YouTube, even if you could afford the bandwidth and keep users from having to watch ad-rolls--self-hosted and the YouTube algorithm will punish you.
A huge part of the high profits portions of the economy is based on this kind of winner take all capture.